1. Technical Field
The present invention relates to a method for automatically detecting whether there is contrast injection in the aortic root on a fluoroscopy or angiography sequence.
2. Discussion of the Related Art
Aortic valve disease leads to 60,000 surgical aortic valve replacements every year in Europe and even more in the United States. Trans-catheter aortic valve implantation (TAVI) is a minimal invasive surgery, with recent advances in utilizing three-dimensional (3D) models to provide anatomical details and more accurate C-arm angulation. Accurate overlay of 3D models onto fluoroscopy can be achieved by matching a 3D model to the angiography with contrast injection showing the aortic root, as shown in FIG. 1a. Automatic detection of the contrast injection into the aortic root can subsequently trigger two-dimensional (2D)/3D registration automatically during TAVI procedures to compensate for motions such as patient movement and aortic root movement due to the insertion of devices. A seamless workflow for motion compensation is important for TAVI, which is a relatively complicated hybrid-OR application involving a large number of staff, equipment and steps.
A few papers have addressed a workflow for motion compensation in TAVI. For example, in A. Condurache et al., “Fast Detection and Processing of Arbitrary Contrast Agent Injections in Coronary Angiography and Fluoroscopy,” SPIE, 2005, 98 percentile of the vessel map histogram is used as the feature for contrast detection. This simple feature, however, is not normalized and its value can change significantly across different sequences and/or patients, making the subsequent classification task difficult. A likelihood ratio test-based method for contrast detection was proposed in R. Liao et al., “Automatic Detection of Contrast Injection on Fluoroscopy and Angiography for Image guided Trans-Catheter Aortic Valve Implantations (TAVI),” SPIE, 2011. Here, temporal analysis of a contrast feature curve can reliably detect a single contrasted frame for each contrast injection across different patients.